AMD and Imaging: 2 Articles

Ocular Imaging in the CATT

By: Glenn J. Jaffe, MD

The CATT evaluated the equivalency of bevacizumab
(Avastin, Genentech) and ranibizumab
(Lucentis, Genentech) in 1208 patients with
neovascular age-related macular degeneration
(AMD), and compared the efficacy and preservation of
visual acuity of a monthly injection schedule to an asneeded
(prn) injection schedule.1 Both the inclusion criteria
and the treatment protocol required imaging with
fluorescein angiography (FA) and time-domain optical
coherence tomography (TD-OCT).

OCT Imaging Protocol

The CATT study included eyes with previously
untreated choroidal neovascularization (CNV) due to
AMD. Active CNV was determined by leakage as seen
on FA and of fluid within or below the retina, or below
the retinal pigment epithelium (RPE), as seen on
TD-OCT.

Every 28 days for the first year of the study, TD-OCT
was performed to determine whether there were signs of
persistent active CNV, as reflected by intraretinal fluid
(cysts), subretinal fluid, or sub-RPE fluid. Ophthalmologists
at each clinical center made decisions to retreat
patients in the prn groups based on OCT images that
showed fluid, decreased visual acuity, new or persistent
hemorrhages, or leakage on fluorescein angiography
(performed at the discretion of the ophthalmologist). An
OCT Reading Center was established to determine the
outcome measures, which included the change in fluid
and foveal thickness on OCT.

Practical Use of Imaging

The evaluation of whether intraretinal, subretinal, or
sub-RPE fluid is present is standard practice for many
retina specialists. When deciding whether my patients
with AMD require anti-VEGF therapy, I routinely order
FA, color fundus photography, and OCT on the first visit
so that I can use these as reference points for comparison
with future imaging studies.

OCT imaging was a very important part of the CATT
study because it was not just used to determine inclusion in the study, but it was also the primary method
used to determine whether retreatment should be given
in the prn groups. The study protocol directed that
treatment with anti-VEGF should be given if any evidence
of fluid was seen on OCT.

To apply the successful CATT study results in the clinic,
it would be necessary to follow a monthly treatment regimen,
and obtain OCT images only when clinically indicated,
or to obtain OCT images on a monthly basis, and to
treat according to the CATT-defined prn protocol.

Another popular approach to treatment is that of
“treat and extend.” A treat-and-extend approach extends
the intervals between treatments based on the results of
the previous treatment and also relies on OCT findings.

Will SD-OCT Make a Difference

At the beginning of the CATT study, all investigators
used TD-OCT, as that was the imaging modality available
to all of the investigators. For the second year of the study,
the majority of investigators have opted to transition to
spectral-domain (SD) OCT. A CATT substudy is under way
to determine if treatment decisions will differ based on
the use of TD-OCT vs SD-OCT. This will represent the first
time that TD-OCT has been compared with SD-OCT in a
large prospective randomized clinical trial; thus, we are
eager to see the results.

In my practice, OCT is a critical part of my decision-making
process, both at the time of diagnosis and during follow-
up for my patients with AMD, as it is with most other
retinal diseases. OCT is a quick and non-invasive procedure,
the images are relatively easy to obtain, and they provide
vital information for the clinician.

Glenn J. Jaffe, MD, is a Professor of
Ophthalmology in the Vitreoretinal Service and
is Director of the Duke Reading Center at Duke
University Eye Center, Durham, NC. Dr. Jaffe is a
Retina Today Editorial Board member. He may
be reached at jaffe001@mc.duke.edu.

Greater Efficiency With OCT

By: James D. Palmer, MD

The evolution of optical coherence tomography
(OCT) over the past few years has changed the
way ophthalmologists view the eye. The development
of spectral-domain (SD) OCT, which
has faster scan times and higher resolution images, as
well as larger data pools for increased reproducibility, has
transformed the OCT into an essential tool, especially for
retina specialists.

I have found that not only do my patients and my
practice benefit from the objective data available for the
diagnosis of retinal conditions, but also that I can save
time in my large private practice by using SD-OCT.

Maximizing Testing Efficiency

My practice has a significant number of patients with
age-related macular degeneration (AMD) who receive
regular injections of anti-VEGF therapy. Although clinical
trials have shown this therapy to be effective, it requires
the patients to be monitored frequently and regularly,
and this can create quite a burden for the physician. In
most cases, monitoring in clinical trials includes a dilated fundus exam and an SD-OCT scan on each visit.

I have found, however, that SD-OCT imaging is highly
sensitive to detecting recurrences of AMD or fluid that
are apparent before any loss of visual acuity. Subretinal
fluid or cystic edema in the retina is visible earlier in
some cases in SD-OCT images than with a fluorescein
angiogram. Because of this, I have developed a system in
which my patients undergo testing at alternate visits. For
example, on every other visit I perform a fully dilated
fundus examination, and at alternate visits patients
undergo SD-OCT imaging and visual acuity testing, both
of which are performed by a technician and do not
require my presence. I then review all scans afterward to
check for any abnormalities. This system not only helps
with my schedule, but also patients prefer the efficiency
of not having to have their eyes dilated at every visit.

It is important to note, however, that it is difficult to
see small hemorrhages with OCT. In my experience, however,
it is rare that these small hemorrhages are the sole
indicators of neovascular activity—cystic edema and/or
subretinal fluid is usually also present.

Summary

I have 6 offices and use a variety of SD-OCT machines
including the Cirrus HD-OCT (Carl Zeiss Meditec),
Spectralis (Heidelberg), and RTVue (Optovue).

Figures 1 and 2 show RTVue images that I used to guide
retreatment. Overall, I have found that SD-OCT’s noninvasive
nature, the simplicity of its operation for technicians,
and the excellent quality of the scans that it produces have
improved my overall practice efficiency while maintaining
my ability to provide the best care for my patients.

James D. Palmer, MD, is a retinal specialist at
Northern California Retina Vitreous Associates.
He may be reached at+1 650 988 7480; or via
email at palmerjdp@gmail.com.

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Retina Today is a publication that delivers the latest research and clinical developments from areas such as medical retina, retinal surgery, vitreous, diabetes, retinal imaging, posterior segment oncology and ocular trauma. Each issue provides insight from well-respected specialists on cutting-edge therapies and surgical techniques that are currently in use and on the horizon.